We all know that atoms are spherical in shape. So,
even if they are packed together there must be
some space lying between them. So this space needs
to be vacuum. And since vacuum contains dark
energy, can we find all the things we need to know
about vacuum by just looking between the atoms
rather than going into the space?

Question Date: 2018-09-23

Answer 1:

Over the last hundred years or so, our
understanding of atoms has changed
drastically. Since the ancient Greeks, people
have speculated that matter might be made up of
atoms. However, our modern understanding of the
structure of atoms began with the discovery of the
electron and the proton, a little over one
hundred years ago. After those discoveries, people
began to propose models for what atoms might look
like, and how the positive protons and the
negative electrons might be arranged. As time went
on and more experiments were performed, the
models describing the atoms were updated to be
consistent with the experimental results. For
example, the neutron was discovered!

Eventually, a model was
proposed in which the protons and neutrons were
concentrated in a tiny core at the center of the
atom, with electrons orbiting around the core
like planets in our solar system orbiting around
the sun.

To describe the motion of the electrons and
the behavior of atoms in general, a new branch of
physics was developed: quantum mechanics.
This model did describe atoms as containing mostly
empty space. However, experiments continued
to be performed, and this model for the atom, and
the quantum mechanics describing it, continued to
be updated.

Today, we still agree that
protons and neutrons are located at the center of
atoms, but the locations of electrons are much
less clearly defined. In fact, one of the core
principles of quantum mechanics is that electrons
don’t actually have a defined position.
Instead, if you perform an experiment to look for
the location of an electron in an atom, you will
sometimes find it in one location, and sometimes
in another, and you will never be able to predict
exactly where you will find it. Instead, you can
only specify the probability that you will find
the electron at a certain location.

Therefore, atoms can’t be
said to contain a vacuum inside, since at any
location there is some probability that an
electron will be there. So, if you are looking
for a vacuum, you need to find a place where there
are no atoms at all!

Sincerely,

p.s.
To complicate things, some people believe that
electrons actually do have a defined position, and
we just haven’t been able to perform the right
measurements to find them. This is an area of
open research.